Thermal and Mechanical Behavior of an L-4 Engine 881149
A three-dimensional finite-element model was used to study the thermal and mechanical behavior of an L-4 engine. Engine operation temperatures and the corresponding engine thermal distortions were analyzed. A pertinent set of thermal boundary conditions, in this case the heat transfer coefficients, was determined using information obtained from Woschni's universal heat transfer coefficient model (1) as well as the experimental results on temperature and heat flux measurements conducted by Enomoto, et al. (2).
A parallel experimental program to measure transient and steady state engine operating temperatures was performed in this study. An AGA 680 Thermovision System was used to measure the outside surface temperatures while forty-nine thermocouples were installed at various parts of the engine to measure the metal internal temperatures. The transient temperature data were used to calculate the heat flux and, hence, heat transfer coefficients using the inverse heat transfer technique.
The calculated engine block and head temperatures compared fairly well with the measured data. Based on the calculated temperature distribution, a cylinder bore thermal distortion of 0.08 mm diametrically was predicted under high load conditions. Distortions due to different deck and bore configurations were also analyzed and are presented in this report.